Bandwidth usage of Sametime 8.5.x

Presence/chat: Peak usage of 300 bits per sec per user. This is based on our standard mixed workload of status changes, chats, file transfers, etc. So for a population of 10,000 users, expect 3 mbit/sec bandwidth usage.

Meetings: Peak usage of 50 kbit/sec to 90 kbit/sec per user; average usage is 10 kbit/sec - 30 kbit/sec per user. This does not include AV. This is based on a workload that is 50% appshare and 50% docshare. For 1000 concurrent meetings users, the peak bandwidth will be 50 - 90 mbit/sec, and average bandwidth will range from 10 - 30 mbit/sec.

Audio/Video: Our rule of thumb is 30 kbit/sec per audio call leg, and 384 kbit/sec per video call leg. These values will chnage based on the codecs and video resolution. For 1-1 calls, the way it works is I send you 1 stream, and you send me 1 stream; for a 1-1 audio call that is 2 30 kbit streams, or 60 kbit. 1-1 video works the same way; total BW is 2 x 384 kbit/sec or 768 kbit/sec. 100 concurrent 1-1 audio calls will take 6 mbit/sec , while 100 concurrent AV calls will take 6 + 77 mbit sec -- 6 mbit for the audio portion and 77 mbit for the video portion.

Multiway calls are harder to calculate. If you are using a video MCU like Polycom, the calculation is similar to that for 1-1 calls; each person gets an outbound stream and an inbound stream. With Sametime Standard AV it is a bit more complicated. Each participant receives up to 5 audio streams. This is because of how the ST Standard system works, we don't mix on a server, we mix on the client. Everyone will send 1 outbound audio stream, and then receive up to 5 inbound streams. For video everyone receives 1 inbound stream, but we only send video when we are the active speaker. So for multi-way calls we can say there are on average 3.5 audio streams and 1.25 video streams per participant; this is bandwidth of 105 kbit/sec for audio and 480 kbit/sec for video, or 585 mbit/sec total per participant.